static lzma_ret
block_encoder_init(lzma_coder *coder, const lzma_allocator *allocator)
{
// Prepare the Block options. Even though Block encoder doesn't need
// compressed_size, uncompressed_size, and header_size to be
// initialized, it is a good idea to do it here, because this way
// we catch if someone gave us Filter ID that cannot be used in
// Blocks/Streams.
coder->block_options.compressed_size = LZMA_VLI_UNKNOWN;
coder->block_options.uncompressed_size = LZMA_VLI_UNKNOWN;
return_if_error(lzma_block_header_size(&coder->block_options));
// Initialize the actual Block encoder.
return lzma_block_encoder_init(&coder->block_encoder, allocator,
&coder->block_options);
}
static lzma_ret
block_encode_uncompressed(lzma_block *block, const uint8_t *in, size_t in_size,
uint8_t *out, size_t *out_pos, size_t out_size)
{
size_t in_pos = 0;
uint8_t control = 0x01; // Dictionary reset
lzma_filter *filters_orig;
// TODO: Figure out if the last filter is LZMA2 or Subblock and use
// that filter to encode the uncompressed chunks.
// Use LZMA2 uncompressed chunks. We wouldn't need a dictionary at
// all, but LZMA2 always requires a dictionary, so use the minimum
// value to minimize memory usage of the decoder.
lzma_options_lzma lzma2 = { LZMA_DICT_SIZE_MIN };
lzma_filter filters[2];
filters[0].id = LZMA_FILTER_LZMA2;
filters[0].options = &lzma2;
filters[1].id = LZMA_VLI_UNKNOWN;
// Set the above filter options to *block temporarily so that we can
// encode the Block Header.
filters_orig = block->filters;
block->filters = filters;
if (lzma_block_header_size(block) != LZMA_OK) {
block->filters = filters_orig;
return LZMA_PROG_ERROR;
}
// Check that there's enough output space. The caller has already
// set block->compressed_size to what lzma2_bound() has returned,
// so we can reuse that value. We know that compressed_size is a
// known valid VLI and header_size is a small value so their sum
// will never overflow.
assert(block->compressed_size == lzma2_bound(in_size));
if (out_size - *out_pos
< block->header_size + block->compressed_size) {
block->filters = filters_orig;
return LZMA_BUF_ERROR;
}
if (lzma_block_header_encode(block, out + *out_pos) != LZMA_OK) {
block->filters = filters_orig;
return LZMA_PROG_ERROR;
}
block->filters = filters_orig;
*out_pos += block->header_size;
// Encode the data using LZMA2 uncompressed chunks.
while (in_pos < in_size) {
size_t copy_size;
// Control byte: Indicate uncompressed chunk, of which
// the first resets the dictionary.
out[(*out_pos)++] = control;
control = 0x02; // No dictionary reset
// Size of the uncompressed chunk
copy_size = my_min(in_size - in_pos, LZMA2_CHUNK_MAX);
out[(*out_pos)++] = (copy_size - 1) >> 8;
out[(*out_pos)++] = (copy_size - 1) & 0xFF;
// The actual data
assert(*out_pos + copy_size <= out_size);
memcpy(out + *out_pos, in + in_pos, copy_size);
in_pos += copy_size;
*out_pos += copy_size;
}
// End marker
out[(*out_pos)++] = 0x00;
assert(*out_pos <= out_size);
return LZMA_OK;
}
static lzma_ret
block_encode_normal(lzma_block *block, lzma_allocator *allocator,
const uint8_t *in, size_t in_size,
uint8_t *out, size_t *out_pos, size_t out_size)
{
size_t out_start;
lzma_next_coder raw_encoder = LZMA_NEXT_CODER_INIT;
lzma_ret ret;
// Find out the size of the Block Header.
block->compressed_size = lzma2_bound(in_size);
if (block->compressed_size == 0)
return LZMA_DATA_ERROR;
block->uncompressed_size = in_size;
return_if_error(lzma_block_header_size(block));
// Reserve space for the Block Header and skip it for now.
if (out_size - *out_pos <= block->header_size)
return LZMA_BUF_ERROR;
out_start = *out_pos;
*out_pos += block->header_size;
// Limit out_size so that we stop encoding if the output would grow
// bigger than what uncompressed Block would be.
if (out_size - *out_pos > block->compressed_size)
out_size = *out_pos + block->compressed_size;
// TODO: In many common cases this could be optimized to use
// significantly less memory.
ret = lzma_raw_encoder_init(
&raw_encoder, allocator, block->filters);
if (ret == LZMA_OK) {
size_t in_pos = 0;
ret = raw_encoder.code(raw_encoder.coder, allocator,
in, &in_pos, in_size, out, out_pos, out_size,
LZMA_FINISH);
}
// NOTE: This needs to be run even if lzma_raw_encoder_init() failed.
lzma_next_end(&raw_encoder, allocator);
if (ret == LZMA_STREAM_END) {
// Compression was successful. Write the Block Header.
block->compressed_size
= *out_pos - (out_start + block->header_size);
ret = lzma_block_header_encode(block, out + out_start);
if (ret != LZMA_OK)
ret = LZMA_PROG_ERROR;
} else if (ret == LZMA_OK) {
// Output buffer became full.
ret = LZMA_BUF_ERROR;
}
// Reset *out_pos if something went wrong.
if (ret != LZMA_OK)
*out_pos = out_start;
return ret;
}
